Additional Information

The UC1903 family of quad supply and line monitor
integrated circuits will respond to under- and
over-voltage conditions on up to four continuously
monitored voltage levels. An internal op-amp inverter
allows at least one of these levels to be negative. A
separate line/switcher sense input is available to
provide early warning of line or other power source failures.

The fault window adjustment circuit on these devices
provides easy programming of under and over-voltage thresholds.
The thresholds, centered around a precision 2.5V reference
have an input hysteresis that scales with the window width for
precise, glitch-free operation. A reference output pin
allows the sense input fault windows to be scaled
independently using simple resistive dividers.

The three open collector outputs on these devices
sink in excess of 30 mA of load current when active.
The under- and over-voltage outputs respond after
separate, user defined, delays to respective fault
conditions. The third output is active during any fault
condition including under- and over-voltage,
line/switcher faults, and input supply under-voltage.
The off state of this output indicates a "power OK"
situation.